Obviously he is a lier. I wouldn't trust him at all. You need to leave him and rebuild your life for yourself and your baby. I know it is scary, and not so easy to think about being alone right now, but it is the best thing you can do.
im sorry for u to go through something like that. for him to continue to distrespect u is obviously showing u he has no respect for u. maybe hes trying to have u and her. he is prbly already in a relationship with her and just cant admit to you. maybe its best to stay as friends and just see what happens from there. maybe even talk to the other lady as adults and maybe ask her if there in a relationship that hes not being honest about it and u just wanna know so u dont have to be caught in the middle of it... best luck :)
I don't think this is appropriate for this app. Sorry to hear that you're dealing with all of that. But this is supposed to be baby related.